A pressure sensor detects pressure difference between detecting pressure and atmospheric pressure or fluid pressure and converts the detected pressure difference into an electric signal. The pressure sensor can be utilized to measure pressures of gases or liquids and possesses a wide range of applications such as flow systems in turbochargers and so forth. Pressure measurements typically are made as absolute, gauge or differential (or relative) measurements. A differential pressure sensor measures the differential measurements between two or more pressures, introduced as inputs to the sensing unit. For example, in gas turbocharger system the pressure difference between the two sides of oil seal needs to be detected for oil leakage prevention.
The majority of prior art differential pressure sensors possess a fixed or stationary electrode formed as a base for the sensing unit, and a dielectric material, which can be a fluid, supported thereon. A conductive outer plate, for example, may be movably mounted on the dielectric material and can be exposed to a pressure condition, which in some cases can cause the dielectric material to flex, with a corresponding change in the capacitance characteristic. Such differential pressure sensing systems are difficult to manufacture and can be easily contaminated by environmentally born dust and the like, resulting in some extreme cases, for example, in shorting of the system. In addition, leakage of a fluid dielectric in such sensors can also dramatically change the system characteristics. Additionally, such differential pressure sensors are too large to be embedded within very small flow systems for on-site monitoring. For example, in turbochargers applications where the total mounting area may be millimeter-sized, for both the sensor and the tube, the use of such conventional pressures is not appropriate. Moreover, such differential pressure sensors are too expensive to be embedded into vehicle turbochargers for oil leakage prevention.
Based on the foregoing, it is believed that a need exists for an improved method and system for sensing differential pressure with an elastomer. A need also exits for a low cost, miniaturized differential pressure sensor, which is capable of being embedded within a small flow system to detect a pressure difference, as described in greater detail herein.